This invention relates to leak tolerant liquid cooling systems for electrical components.
In the prior art, one such liquid cooling system is described in U.S. Pat. No. 4,698,728 which is assigned to the present assignee. There, a liquid coolant is directed past the electrical components via certain conduits at sub-atmospheric pressure. Since the pressure of the liquid inside of the conduits is less than the pressure of the atmosphere outside the conduits, air gets sucked into the conduits if they develop a leak. Consequently, none of the liquid coolant is spilled.
However, after the air gets into the conduits, it must somehow be purged from them. Otherwise, if the air is allowed to remain entrained in the coolant, the rate at which the coolant moves through the system would be reduced which in turn would reduce the systems cooling ability. Also, the air could get trapped in certain critical passages of the cooling system, such as passages in a cooling jacket around the electrical components, which in turn would cause hot spots in the cooling system.
In the above referenced patent '728, the preferred mechanism by which air is removed from the coolant is illustrated and described in conjunction with FIGS. 2a-2d. However, with that mechanism, a pump which circulates the liquid coolant through the conduits must be temporarily turned off and then turned back on in order to perform the air purging operation.
Such an interruption in the operation of the pump is undesirable because it temporarily lowers the rate at which the coolant flows through the system, and that in turn lowers the rate at which the electrical components are cooled. In addition, switching the pump from off to on produces pressure surges throughout the cooling circuit, and that in turn stresses the cooling circuit components and their joints. Further, switching the pump from off to on produces a step like increase in electrical power which is drawn from the cooling system's power supply; and thus the power supply must include compensation to insure that harmful transients do not occur in any supply voltages to the electrical components that are being cooled.
Accordingly, the primary object of the invention is to provide an improved leak tolerant cooling system is which the above described deficiencies are eliminated.